AbstractsEngineering

Traditionally, distribution networks only have a single source upstream with loads con- nected downstream so the network parameters are well known and the network can be protected using relatively inexpensive devices such as fuses. With the advent of distribu- tion generation (DG), storage, microgrids and scenarios such as islanding in distribution networks new protection schemes will be required. The advent of smart grids also creates opportunities for improved protection schemes. The main goal of this research was to investigate future smart grids with regards to the challenges they will face with protection. To achieve this the distribution network was investigated in terms of its topology, protection devices and protection schemes which are currently implemented. Next, new advances such as smart grids, distributed gener- ation and the challenges and opportunities this will create in the distribution network were investigated. To investigate the type of faults and fault waveforms likely to be encountered by protective devices in future distribution networks a distribution feeder was simulated in PSCAD with distributed generation (DG). The types of faults that may occur were analysed and fault waveforms generated and analysed. It was observed that a decaying DC o set is a signi cant component in the fault waveforms when DG was added to a distribution network. The level of the decaying DC o set was shown to be inversely proportional to the series impedance between the source and fault to ground which includes the impedance of the source, the distribution line and the fault impedance. The instant in which the fault occurs also has a large e ect on the peak level of the decaying DC o set in the fault current waveform with the highest peaks occurring at a phase o set of 3PI/ 4 and 3 PI/ 2 .